Infrared Imaging for Health Monitoring Applications
One of the research efforts supported by the SST Partnership is to develop an inexpensive yet sensitive IR sensor to be used in imaging applications. This research is led by Professors Otto Gregory and Bill Euler in collaboration with Teltron Technologies, Inc. (Birdsboro, PA, a subsidiary of Video Display Corporation). The IR sensor is based upon a ferroelectric and pyroelectric polymer, poly(vinylidene difluoride), commonly referred to as PVDF. In this application, the pyroelectric effect is exploited to create the sensor. The IR sensor is used in a vidicon tube to create the image.
The sensor is unique compared to other common IR detectors because it is inexpensive, sensitive, and can respond to a broad wavelength range. In tests done at URI, the IR sensitivity appears to be constant throught the wavelength range from ~1 micron to 25 microns. Although the sensor does not reach the sensitivity of the best semiconductor detectors, the polymer sensor does not require cooling to cryogenic temperatures.
Initial sensors have been tested in health monitoring applications. Since the system will be low cost (at mass production, it is estimated that the cost of the whole IR imaging system will be $5,000 or less), it should be affordable for nearly any medical or vetinary facility. IR imaging has the potential to be an effective tool for health monitoring because of temperature differences found across tissues in the body when a person is not completely healthy. For example, if there are circulatory problems, then the temperature in this region drops and an IR image looks darker. In contrast, if there is an inflammation, the temperature is higher and the IR image appears lighter. Examples of this are given below.
In the first example, the IR images of the heads of a healthy individual and a person with sinus problems are shown.
The bright and uniform image of the healthy person indicates no inflammations or circulatory problems. In conparison, the large dark spot on the center of the face of the person on the right clearly indicates blocked sinuses.
The second image shows a person who has successfully been treated for throat cancer.
In this case, the image is not nearly as bright and there is a localized dark spot (just above the T in Scar Tissue) where radiation damage from the cancer treatment has formed scar tissue. The overall lower brightness of the face suggests other circulatory problems or scar tissue may also be present.
In the final example, the image of the lower back of an individual suffering back pain is shown.
The bright white region across the upper middle portion of the image shows the inflamed area. This image was taken using the IR camera with the person fully clothed, demonstrating the sensitivity of the sensor.
Support for this research has been provided by Teltron Technologies, Inc. and the URI Foundation.